In an impassioned love letter to cities and their political leaders, Barber (Jihad vs. McWorld) celebrates the diversity and ferment that embody urban life. Modern cities, he claims, fulfill the promises of John Dewey and Walt Whitman’s paeans to democracy by allowing “democratic voices, ardent dreamers and lawless artists” to inspire each other. It is not always clear how mayors fit into this tumult of roiling humanity, but Barber calls them “possibly the best hope we have for the survival of democracy across borders.” By focusing on practical solutions to the day-to-day problems that affect their constituents, mayors champion a mode of governance characterized by collaboration and consensus, and the global ties they create offer a more human-centered, applied style of politics than the contentiousness of national legislatures or the bureaucratic talking shops of the U.N. and European Union, according to the author. Barber is more interested in crafting a metaphysics of urban life than the down-to-earth minutiae of local stewardship (he derides congestion pricing schemes, markedly successful in many cities, as “keeping-the-poor-from-driving plan[s]” without offering any realistic alternative), and in the throes of his “longing for and expectation of an interdependent urbanity as encompassing as humanity’s perfervid imagination,” he neglects to notice that many of his castles are planted firmly in the air. Agent: Steve Wasserman, Kneerim, Williams & Bloom. (Nov.)